A shock absorber can comprise a cylinder and a piston received in the cylinder for reciprocation within the cylinder. The piston can typically divide the cylinder into two opposed chambers, one chamber being defined on one side of the piston within the cylinder and the other chamber being defined on an opposed side of the piston within the cylinder. A piston shaft is typically connected to the piston and extends from the piston to a position outside of the cylinder. An appropriate fluid, such as oil, or air, or the like, is normally contained in the chambers.
In use, the fluid passes between the chambers in response to reciprocation of the piston in the cylinder to effect damping.
Typical shock absorbers can provide two kinds of damping: compression damping (xe2x80x9cCDxe2x80x9d), and rebound damping (xe2x80x9cRDxe2x80x9d). One normally refers to damping force created during xe2x80x9cinwardxe2x80x9d travel of the shaft (shortening of the shock) and the other normally refers to damping force created during xe2x80x9coutwardxe2x80x9d travel of the shaft (lengthening of the shock). Generally, but not alwaysxe2x80x94depending on, for example, a linkage connecting the shock absorber to, for example, a vehicle, or the likexe2x80x94RD applies during outward motion of the shaft relative to the cylinder and CD applies during inward motion of the shaft relative to the cylinder.
For typical shock absorbers, these RD and CD forces vary depending on the velocity of the piston as it displaces in opposed directions within the cylinder during reciprocation. Because the piston is normally directly connected to the shaft, RD and CD forces also depend on shaft velocity. The key RD and CD characteristics of a shock absorber can be represented on a graph plotting damping force against velocity. Since RD and CD forces are usually required to be quite different, CD forces can typically be only 10% to 50% of RD forces for the same piston velocity during piston strokes in opposed directions in the cylinder. Accordingly, two separate curves, or profiles, are often provided on such a graph for an associated shock absorber to represent RD and CD forces relative to piston velocity in the cylinder for the associated shock absorber.
The RD and CD force characteristics, or profiles, for a shock absorber can have a major effect on the quality of performance provided by a shock absorber for a given application. In a given application, the ideal force profiles depend on a variety of factors. For example, on a factory-produced full-suspension mountain bicycle, the ideal damping force requirements or profiles can vary depending on (among other things) factors such as rider weight, rider skill, the particular terrain conditions, and the like.
Since such factors are extraneous to the bicycle, it would be desirable to provide a shock absorber with easily-adjustable RD and/or CD characteristics or values to enable a user of the mountain bicycle to adjust the RD and CD characteristics of the shock absorber. Accordingly, it would be advantageous to provide shock absorbers that are externally adjustable by the user.
Some adjustable shock absorbers provide for RD force adjustment only. Others provide for CD force adjustment only. And some provide for both RD and CD force adjustment. Typical shock absorbers that provide for both RD and CD force adjustment usually provide for one of the adjustments at an end of the shaft. The adjustment (whether made by knob, screw, lever, etc.) is usually communicated with a working portion of the shock absorber (for example, the piston) by means of a component extending down a center of the piston shaft. A common design uses a small adjuster rod (typically xe2x85x9xe2x80x3 in diameter) which extends down the center of a tubular shaft (typically having a ⅝xe2x80x3 outer diameter (OD) and a slightly greater than xe2x85x9xe2x80x3 inner diameter (ID)). Adjustment is commonly made in either of two ways: a) the adjuster rod is moved axially (up or down) to alter damping (usually RD, on some designs CD) or, b) the adjuster rod is rotated to alter damping. There are various designs to convert the axial motion or the rotary motion into increased or decreased damping.
Many double-adjustable shock absorber designs only provide for the adjustment of one of the CD or RD characteristics of the shock absorber at the piston shaft end. The adjustment of the other of the CD and RD is then provided at another location, sometimes at an external fluid reservoir operatively connected to the shock absorber, for example. One manufacturer, FOX FACTORY, INC., of San Jose, Calif., for example, has been making an adjustable shock absorber which provides for adjustment of RD and CD. Such a shock absorber has been sold as the Twin-Clicker for over 15 years. The Twin-Clicker shock absorber provides RD adjustment at the shaft end (via axial motion of a central adjuster rod) and CD adjustment at the external fluid reservoir (connected to the shock absorber via a high-pressure hose).
It has been found that providing such double adjustment of a shock absorber at locations relatively far removed from each other is rather inconvenient for a user. Accordingly, a double-adjustable shock absorber design which provides for adjustment of both RD and CD at the shaft end is much more convenient and is thus very desirable. One such shaft-end double-adjustable shock absorber design uses two separate adjuster rods, which extend down a piston shaft, offset pins, and the like. This design is complicated and difficult to produce. Another shaft-end double-adjustable shock absorber design uses two concentric adjuster rods (one inside the other). This design requires two adjuster rods and a sufficiently large inside diameter within the piston shaft to provide room for both rods. An example of the two concentric adjuster rod design can be found in a shock absorber currently sold by Cane Creek of Fletcher, N.C.
According to one aspect of the invention, there is provided a shock absorber, comprising first and second parts, the first part comprising a cylinder having an interior, the second part comprising a piston, having first and second sides, received in the cylinder for reciprocation, the piston dividing the interior of the cylinder into a first chamber on the first side of the piston and a second chamber on the second side of the piston. The shock absorber further comprises at least one passage extending between and fluidly coupling the first and second chambers, a fluid contained in the first and second chambers, the first and second chambers being in fluid flow communication with each other through the passage in response to reciprocation of the piston in the cylinder. The shock absorber yet further comprises an adjustment component which is mounted to a chosen one of the first and second parts for adjustment within first and second degrees of freedom of movement relative to the chosen one of the first and second parts, such that when the adjustment component is adjusted within the first degree of freedom of movement, a resistance to fluid flow through the at least one passage from the first chamber to the second chamber is varied, and when the adjustment component is adjusted within the second degree of freedom of movement, resistance to fluid flow through the at least one, passage from the second chamber to the first chamber is varied.
According to another aspect of the invention, a method of adjusting the operation of a shock absorber is provided, the shock absorber comprising first and second parts, the first part comprising a cylinder having an interior and the second part comprising a piston reciprocally received in the cylinder, the piston dividing the interior of the cylinder into first and second chambers, and at least one passage fluidly coupling the first and second chambers on opposite sides of the piston. The method comprises adjusting selectively the position of an adjustment component, mounted to one of the first and the second parts, within a first degree of freedom of movement relative to the one of the first and second parts of the shock absorber to thereby adjust resistance to fluid flow through the at least one passage from the first chamber to the second chamber, and adjusting selectively the position of the adjustment component within a second degree of freedom of movement relative to the one of the first and second parts of the shock absorber to thereby adjust resistance to fluid flow through the at least one passage from the second chamber to the first chamber.
According to a further aspect of the invention, there is provided a shock absorber comprising a damping fluid cylinder, a damping piston slidably mounted within the cylinder and a shaft having an inner end connected to the damping piston for movement of the piston within the cylinder in first and second directions. The damping piston comprises a flow path therethrough and a variable restriction flow restrictor along the flow path. The shock absorber further comprises a damping adjuster having an axis extending along the shaft, a damping adjuster rotator operably coupled to the damping adjuster for rotating the damping adjuster about said axis and a damping adjuster driver operably coupled to the damping adjuster for longitudinally moving the damping adjuster along said axis. The damping adjuster is operably coupled to the flow restrictor so rotational and longitudinal movement of the damping adjuster separately operates the flow restrictor thereby separately changing the damping of the shock absorber during movement of the piston.
According to yet a further aspect of the invention, a shock absorber is provided, the shock absorber comprising a damping fluid cylinder, a vented piston slidably mounted within the cylinder and a hollow shaft having an inner end connected to the vented piston for movement of the piston within the cylinder in first and second directions. The vented piston comprises first and second flow paths which can open as the piston moves in the first and second directions, respectively, and first and second variable restriction flow restrictors along respective ones of the first and second flow paths. The shock absorber further comprises a damping adjuster rod, having a rod axis, extending through the hollow shaft, a rod rotator operably coupled to the rod for rotating the rod about the rod axis and a rod driver operably coupled to the rod for longitudinally moving the rod along the rod axis. The rod is operably coupled to the first and second flow restrictors so rotational and longitudinal movement of the rod operates the first and second flow restrictors, respectively, thereby separately changing the damping of the shock absorber as the piston moves in the first and second directions.
According to yet another aspect of the invention, there is provided a method of adjusting the operation of a shock absorber, the shock absorber comprising an adjustment component mounted for adjustment within at least two degrees of freedom of movement, the method comprising adjusting selectively the position of the adjustment component within one of the degrees of freedom of movement thereby to adjust resistance to fluid flow through a passage and adjusting selectively the position of the adjustment component within the other degree of freedom of movement thereby to adjust resistance to fluid flow through another passage.
According to yet a further aspect of the invention, there is provided a method of adjusting the operation of a shock absorber, the shock absorber comprising a cylinder, a piston received in the cylinder for reciprocation, a first chamber defined in the cylinder on one side of the piston, a second chamber defined in the cylinder on an opposed side of the piston, a fluid contained in the chambers, at least one passage extending between the chambers, through which passage fluid passes between the chambers in response to reciprocation of the piston in the cylinder, in use, the shock absorber further comprising an adjustment component mounted for adjustment within at least two degrees of freedom of movement, the method comprising adjusting selectively the position of the adjustment component within one of the degrees of freedom of movement thereby to adjust resistance to fluid flow through a passage and adjusting selectively the position of the adjustment component within the other degree of freedom of movement thereby to adjust resistance to fluid flow through another passage.